diff options
| -rw-r--r-- | drivers/i2c/busses/i2c-stm32.c | 153 | ||||
| -rw-r--r-- | drivers/i2c/busses/i2c-stm32.h | 37 |
2 files changed, 190 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-stm32.c b/drivers/i2c/busses/i2c-stm32.c new file mode 100644 index 000000000000..d75fbcbf02ef --- /dev/null +++ b/drivers/i2c/busses/i2c-stm32.c @@ -0,0 +1,153 @@ +/* + * i2c-stm32.c + * + * Copyright (C) M'boumba Cedric Madianga 2017 + * Author: M'boumba Cedric Madianga <[email protected]> + * + * License terms: GNU General Public License (GPL), version 2 + */ + +#include "i2c-stm32.h" + +/* Functions for DMA support */ +struct stm32_i2c_dma *stm32_i2c_dma_request(struct device *dev, + dma_addr_t phy_addr, + u32 txdr_offset, + u32 rxdr_offset) +{ + struct stm32_i2c_dma *dma; + struct dma_slave_config dma_sconfig; + int ret; + + dma = devm_kzalloc(dev, sizeof(*dma), GFP_KERNEL); + if (!dma) + return NULL; + + /* Request and configure I2C TX dma channel */ + dma->chan_tx = dma_request_slave_channel(dev, "tx"); + if (!dma->chan_tx) { + dev_dbg(dev, "can't request DMA tx channel\n"); + ret = -EINVAL; + goto fail_al; + } + + memset(&dma_sconfig, 0, sizeof(dma_sconfig)); + dma_sconfig.dst_addr = phy_addr + txdr_offset; + dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + dma_sconfig.dst_maxburst = 1; + dma_sconfig.direction = DMA_MEM_TO_DEV; + ret = dmaengine_slave_config(dma->chan_tx, &dma_sconfig); + if (ret < 0) { + dev_err(dev, "can't configure tx channel\n"); + goto fail_tx; + } + + /* Request and configure I2C RX dma channel */ + dma->chan_rx = dma_request_slave_channel(dev, "rx"); + if (!dma->chan_rx) { + dev_err(dev, "can't request DMA rx channel\n"); + ret = -EINVAL; + goto fail_tx; + } + + memset(&dma_sconfig, 0, sizeof(dma_sconfig)); + dma_sconfig.src_addr = phy_addr + rxdr_offset; + dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + dma_sconfig.src_maxburst = 1; + dma_sconfig.direction = DMA_DEV_TO_MEM; + ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig); + if (ret < 0) { + dev_err(dev, "can't configure rx channel\n"); + goto fail_rx; + } + + init_completion(&dma->dma_complete); + + dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n", + dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx)); + + return dma; + +fail_rx: + dma_release_channel(dma->chan_rx); +fail_tx: + dma_release_channel(dma->chan_tx); +fail_al: + devm_kfree(dev, dma); + dev_info(dev, "can't use DMA\n"); + + return NULL; +} + +void stm32_i2c_dma_free(struct stm32_i2c_dma *dma) +{ + dma->dma_buf = 0; + dma->dma_len = 0; + + dma_release_channel(dma->chan_tx); + dma->chan_tx = NULL; + + dma_release_channel(dma->chan_rx); + dma->chan_rx = NULL; + + dma->chan_using = NULL; +} + +int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma, + bool rd_wr, u32 len, u8 *buf, + dma_async_tx_callback callback, + void *dma_async_param) +{ + struct dma_async_tx_descriptor *txdesc; + struct device *chan_dev; + int ret; + + if (rd_wr) { + dma->chan_using = dma->chan_rx; + dma->dma_transfer_dir = DMA_DEV_TO_MEM; + dma->dma_data_dir = DMA_FROM_DEVICE; + } else { + dma->chan_using = dma->chan_tx; + dma->dma_transfer_dir = DMA_MEM_TO_DEV; + dma->dma_data_dir = DMA_TO_DEVICE; + } + + dma->dma_len = len; + chan_dev = dma->chan_using->device->dev; + + dma->dma_buf = dma_map_single(chan_dev, buf, dma->dma_len, + dma->dma_data_dir); + if (dma_mapping_error(chan_dev, dma->dma_buf)) { + dev_err(dev, "DMA mapping failed\n"); + return -EINVAL; + } + + txdesc = dmaengine_prep_slave_single(dma->chan_using, dma->dma_buf, + dma->dma_len, + dma->dma_transfer_dir, + DMA_PREP_INTERRUPT); + if (!txdesc) { + dev_err(dev, "Not able to get desc for DMA xfer\n"); + ret = -EINVAL; + goto err; + } + + reinit_completion(&dma->dma_complete); + + txdesc->callback = callback; + txdesc->callback_param = dma_async_param; + ret = dma_submit_error(dmaengine_submit(txdesc)); + if (ret < 0) { + dev_err(dev, "DMA submit failed\n"); + goto err; + } + + dma_async_issue_pending(dma->chan_using); + + return 0; + +err: + dma_unmap_single(chan_dev, dma->dma_buf, dma->dma_len, + dma->dma_data_dir); + return ret; +} diff --git a/drivers/i2c/busses/i2c-stm32.h b/drivers/i2c/busses/i2c-stm32.h index d4f9cef251ac..868755f82f88 100644 --- a/drivers/i2c/busses/i2c-stm32.h +++ b/drivers/i2c/busses/i2c-stm32.h @@ -11,6 +11,10 @@ #ifndef _I2C_STM32_H #define _I2C_STM32_H +#include <linux/dma-direction.h> +#include <linux/dmaengine.h> +#include <linux/dma-mapping.h> + enum stm32_i2c_speed { STM32_I2C_SPEED_STANDARD, /* 100 kHz */ STM32_I2C_SPEED_FAST, /* 400 kHz */ @@ -18,4 +22,37 @@ enum stm32_i2c_speed { STM32_I2C_SPEED_END, }; +/** + * struct stm32_i2c_dma - DMA specific data + * @chan_tx: dma channel for TX transfer + * @chan_rx: dma channel for RX transfer + * @chan_using: dma channel used for the current transfer (TX or RX) + * @dma_buf: dma buffer + * @dma_len: dma buffer len + * @dma_transfer_dir: dma transfer direction indicator + * @dma_data_dir: dma transfer mode indicator + * @dma_complete: dma transfer completion + */ +struct stm32_i2c_dma { + struct dma_chan *chan_tx; + struct dma_chan *chan_rx; + struct dma_chan *chan_using; + dma_addr_t dma_buf; + unsigned int dma_len; + enum dma_transfer_direction dma_transfer_dir; + enum dma_data_direction dma_data_dir; + struct completion dma_complete; +}; + +struct stm32_i2c_dma *stm32_i2c_dma_request(struct device *dev, + dma_addr_t phy_addr, + u32 txdr_offset, u32 rxdr_offset); + +void stm32_i2c_dma_free(struct stm32_i2c_dma *dma); + +int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma, + bool rd_wr, u32 len, u8 *buf, + dma_async_tx_callback callback, + void *dma_async_param); + #endif /* _I2C_STM32_H */ |